Magnetically biased vacuum relay



April 4, 1967 J. "r. PERRY ETAL MAGNETICALLY BIASED VACUUM RELAY 3 Sheets-Sheet 1 Filed Aug. 19, 1964 Fig.

gs sa JOHN TPERHY CHESTERJ KAW/ECK/ lNVE/VTORS BUG/(NORM BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS April 4, 1967 .1. T. PERRY ETAL MAGNETICALLY BIASED VACUUM RELAY I5 Sheets-Sheet 2 Filed Aug. 19, 1964 vl/ K mg pwm TM m WW m C BUG/(HORN, Emma, KLAROU/ST 8 SPAR/(MAN ATTORNEYS April 4, 1967 .1. T. PERRY ETAL 3,312,803

MAGNETICALLY BIASED VACUUM RELAY Filed Aug. 19, 1964 3 Sheets-Sheet 5 JOHN r PERRY 0/155 rm .1. KA w/scx/ lA/VENTORS BUG/(HORN, BLOHE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS United States Patent @flice 3,312,893 Fatented Apr. 4, 1967 3,312,803 MAGNETICALLY BIASED VACUUM RELAY John T. Perry, Melrose Park, and Chester J. Kawiecki, Chicago, 111., assignors t Joslyn Mfg. and Supply C0., Chicagp, HL, a corporation of Illinois Filed Aug. 19, 1964, Ser. No. 390,765 Claims. (Cl. 200-144) The present invention relates to electrical relays, and more particularly to a vacuum relay, or switch.

A primary object of the present invention is to provide a new and improved vacuum relay.

Another object is to provide a vacuum relay capable of operating at relatively high current and voltage loads.

A further object is to provide a vacuum relay in which the operation is independent of the ambient pressure.

Still another object is to provide a vacuum relay that is compact, with parts that can be readily miniaturized.

Another object of the invention is to provide a vacuum relay construction that is inexpensive and that permits of easy and ready manufacture and assembly.

Another object is to provide a relay of extremely rugged construction capable of withstanding severe vibration and shock conditions.

A further object is to provide a vacuum relay having a movable contact element of unusual flexibility, which enables larger manufacturing tolerances in the placement of the fixed contacts which such element engages.

Still another object is to provide a multi-pole vacuum relay construction which minimizes electrical stress between opposed poles thereof.

In furtherance of the above objects and in accordance with an illustrated embodiment, the present relay com prises an evacuated envelope including a glass bulb which supports a movable contact and a pair of fixed contacts spaced apart axially of the envelope. The movable con tact includes a rigid supporting post hermetically sealed in the bulb and a thin, flexible plate-like element extending within the bulb from the post to a position between the two fixed contacts. An actuator rod disposed and movable axially within the envelope is connected at one end to a midportion of the flexible element and at the opposite end to an axially movable magnetic core. The movable core slides within an inner sleeve of a tubular housing hermetically sealed to an open end of the bulb. An inner portion of the housing within the evacuated envelope houses a permanent magnet assembly, while an outer portion of the housing, outside the envelope, houses an electromagnet, including a fixed core, a magnetic shell and a coil within the shell and surrounding the fixed core and sleeve. When the coil is de-energized, the movable core is biased against the permanent magnet whereby the actuator rod is maintained in its axially innermost position and the flexible element is flexed into contact with one of the two fixed contacts. When the coil is energized, the movable core is drawn away from the permanent magnet and the actuator rod outwardly of the bulb, thus flexing the flexible contact in the opposite direction and into contact with the other of the fixed contacts.

The above and other objects and advantages will become more apparent from the following description and the accompanying drawings wherein:

FIG. 1 is a vertical midsectional view through a vacuum relay having a single movable cont-act in accordance with the present invention and showing the relative portions of the magnet elements with the coil in a de-energized condition; 7

FIG. 2 is an end view of the relay of FIG. 1;

FIG. 3 is a fragmentary midsectional view taken along 7 the line 3-3 of FIG. 2 showing the pin connection between the actuator rod and the movable contact;

fit

FIG. 4 is a fragmentary sectional view taken along the line 4-4 of FIG. 1 showing the relative positioning of the two fixed contacts;

FIG. 5 is a fragmentary sectional view of a portion of the housing but showing the relative positions of the magnet elements with the coil in an energized condition;

FIG, 6 is a view of the movable core element and the pin connection between such element and the actuator rod, rotated from their orientation in FIG. 1;

FIG. 7 is a vertical midsectional view through a modified embodiment of the invention; and

FIG. 8 is an end view of the embodiment of FIG. 7.

With reference first to the embodiment of FIGS. 1

through 6 of the drawings, one of the illustrated relays is brazed or welded to an annular, Z-shaped flange 20 formed of a nonmagnetic material such as Monel metal. The flange 20 in turn is hermetically sealed, as by welding, to an annular end plate 22, preferably of the same nonmagnetic material as the flange 20. The end plate 22 supports and is hermetically sealed to a tubular housing 24 of nonmagnetic material, preferably of the same kind as the end plate 22 and flange 20.

The housing 24 is of a substantially smaller outer diameter than the diameter of at least the open end of the glass bulb and is re-entrant, that is, extends partially within the open end of the bulb. The housing includes an internal, radially inwardly projecting flange 26 which at its inner end supports a central sleeve 28 disposed coaxially with respect to the housing and bulb. The flange 26 divides the housing into an inner compartment 30 in communication with the interior of the bulb and forming a part of the evacuated envelope, and an outer compartment 32 which, as will become more apparent hereinafter, does not form part of the evacuated envelope.

An axially polarized permanent ring magnet 34 of preferably ceramic material and having an outer diameter slightly less than the inside diameter of the housing 24 is fixedly mounted within the inner compartment 30 between a shoulder 36 on the inner wall of the housing and a radially inwardly projecting circular plate 38 of magnetic material such as soft iron. The plate 38 has an axially outwardly directul flanged portion 39 defining a central opening into the compartment 30. The plate 38 also functions to define a portion of the magnetic path indicated by the dashed line 40 created by the permanent magnet. A snap ring 42 fits within an annular groove at the inner end of the housing to hold the ring magnet and magnetic plate 38 in a fixed position within the compartment 30.

A movable core 44 of magnetic material is slidably mounted within the sleeve 28 for axial movement toward and away from the permanent magnet 34. The innermost end of the movable core defines a thin radially extending flange 46 which, when the coils of the electromagnet are de-energized, is drawn into abutment with the ring magnet 34 to define a portion of the magnetic path 40 of the permanent magnet. The flange 46 includes an axially inwardly projecting, annular flange 47, shown clearly in FIGS. 5 and 6, which engages the flanged portion 39 of the plate 38 when the coil is deenergized to define a portion of the magnetic path 40 of the permanent magnet.

An electromagnet means is mounted within the lower compartment 32 and includes an axially disposed, fixed core 52 of soft iron or other suitable magnetic material ramic.

and a thin cylindrical shell, or lining, 54 of like material fitting snugly within and against the nonmagnetic housing 24. The shell 54 has an inner end wall 56 which abuts against the flange 26 of the housing and extends radially inwardly to a position closely adjacent the sleeve 28. The shell also has a removable outer end wall 58 having a central opening through which a threaded shaft end 60 of the fixed core extends for receiving a nut 62 which fastens the core and end wall in position. The opposite, inner end 64 of the fixed core fits within and is sealed to the outer end of the sleeve 28 to hermetically seal the inner compartment 30, including the interior of the sleeve, from the outer compartment 32. Thus, the flange 20, end plate 22, housing 24, flange 26, sleeve 28 and inner end 64 of the fixed core cooperate to define an end wall of the evacuated envelope.

A coil 68, a portion of which is shown in FIG. 1, surrounds the fixed core and the portion of the sleeve 28 projecting into the lower compartment 32. When energized, the coil induces a greater magnetic force than that induced by the permanent magnet 34, whereby the movable core 44 is drawn away from the permanent magnet 34 and into abutment with the inner end 64 of the fixed core. Upon de-energization of the coil 68, the now unopposed force induced by the permanent magnet draws the movable core back into abutment with the permanent magnet. This arrangement is particularly advantageous from the standpoint of simplicity of construction and compactness in that the permanent magnet is mounted entirely within the evacuated envelope, and the movable core 44 is also mounted wholly within the envelope but cooperates to define both a part of the electromagnet circuit and a portion of the permanent magnetic circuit.

Fixed to and extending axially inwardly of the bulb from the movable core 44 is an actuator rod 69 formed of an electrically nonconductive material such as a ce- The rod, as evident from FIG. 2, is circular in cross section and is secured to the movable core by a molybdenum pin 70 which extends through the rod and the upstanding flange portion 47 of the movable core as most clearly shown in FIGS. and 6.

A movable contact is-actuated by the actuator rod and includes a rigid rod-like supporting post 72, preferably of tungsten, hermetically sealed in the sidewall 14 of the bulb and extending inwardly and outwardly thereof. Fixed to the inner end of the post 72 by a Monel cap 73 is a thin, plate-like, flexible contact portion, or switching element, 74 which extends radially across the interior of the bulb in a plane generally normal to the axis of the actuatorrod and bulb. The flexible element is made of molybdenum or other conductive material having the desired flexibility for the purpose intended. The outer end portion of the actuator rod 69, as shown in FIGS. 2 and 3, extends through a circular opening in the center of an elongate aperture 76 in the midportion of the flexible element. The rod is secured to the element by a molybdenum cross pin 78 which extends through a transverse opening in the rod and is slotted at each end thereof to receive inner edge portions of the flexible element.

Thus, reciprocation of the movable core 44 through energization and de-energization of the coil actuates the rod 70, which in turn flexes the element 74 between two axially spaced limit positions determined by a pair of fixed contacts 84 and 86. The fixed contacts are in the form of rigid cylindrical rods of tungsten and are hermetically sealed in the tubular sidewall portion 14 of the bulb. As viewed from a plane normal to the axis of the envelope, as in FIG. 2, the fixed contacts extend inwardly and outwardly of the tubular sidewall 14 and angularly across the free end 82 of the flexible element 74, with one of the contacts 84 extending across one broad surface of the flexible element and the other contact 86 extending across the opposite surface thereof. The axes of the fixed contacts lie in planes parallel to one another and to the plane of the switching element, and

normal to the axis of the envelope and'of the actuator rod so that the free end of the element makes line rather than point contact with each fixed contact.

The end portions of the post 72 and fixed contacts 84 and 86 that extend outside the bulb permit electrical connections to be made thereto. The relatively great circumferential spacing of the exterior portions is of advantage in minimizing the possibility of breakdown along the exterior surface of the envelope between connecting posts when high voltage differences may exist between the same. With the foregoing arrangement, the flexible element '74 engages the fixed contact 84 when the coil-is de-energized to complete a circuit between the post 72 and the fixed contact 84. When the coil is energized, however, the flexible element 74 engages the fixed con: tact 86 to complete, if desired, a circuit between post 72 and the contact #36 and open the circuit through contact 84. Upon de-energization of the coil, the flexible element returns into engagement with the contact 84, reopening the circuit between contacts 86 and 72'and closing against the circuit between contacts 72 and 84.

A feature of the foregoing arrangement is the lever action of the actuator rod and flexible contact whereby the actuator rod and movable core are moved through only about one-half the distance that the free end 82 of the flexible contact 74 moves to engage one or the other of the fixed contacts. The minimal travel of the actuator rod and movable core enables the provision of a minimum gap between the fixed and movable cores, thus enabling the electromagnet to overcome the force induced by a very high-strength permanent magnet. The use of a powerful permanent magnet, of course, results in increased vibrational stability of the actuating means when in its de-energized position.

Another feature of the present actuating arrangement is the reduction in accuracy required in positioning the fixed elements, thus reducing the cost of manufacturing the relay. This follows from the fact that the actuating force is applied to the flexible element at its midpoint and the free end of the element engages the fixed contacts. Since the free end can move a relatively great distance between its possible limit positions, the fixed contacts may be spaced with relatively greater latitude within the range of such positions. Furthermore, since the moving force is applied at the midpoint of the flexible element and it is engaged at its opposite ends with its mounting contact and the fixed contacts, the possibility of overstressing of the flexible element is minimized because it is at the midpoint where maximum flexing may occur. Thus, for example, if the spacing between the fixed contacts at the free end of the flexible element should be considerably less than the limits of axial movement of such element so that the center of the flexible element would be forced to move through a greater distance than its free end, no harm would result. The center of the element would simply flex to adjust to the differences in distances traveled by the midportion and free end.

An important advantage of the present permanent magnet return as compared to a bellows return is that the permanent magnet return is operable independently of the ambient pressure, thereby rendering the present relay operable at extremely high altitudes or in a vacuum.

The permanent magnet return is also preferable to a spring or bellows-actuated return for the reason that the former is not subject to fatigue and the relay has greater resistance to vibrational stresses in both the energized and de-energized conditions of the electromagnet. This is true because when the electromagnet is de-energized and the movable core engages the permanent magnet, the permanent magnet exerts its greatest influence on the movable core and therefore the movable contact to hold the latter firmly against the fixed contact 84, whereas a spring at the comparable moment would be extended and therefore exerting a minimum force to hold the movable con tact against the fixed contact. On the other hand, when the electromagnet is energized, the movable core is spaced from the permanent magnet, and therefore the permanent magnet is exerting a minimum influence on the movable core and its associated movable contact at a time when the electromagnet exerts its maximum fence on the same elements. At a comparable moment, however, a spring or bellows would be compressed and thus exerting a maximum force opposing that induced by the electromagnet and tending to draw the movable core away from the electromagnet.

In assembling the relay of FIG. 1, the housing 24 and the elements therewithin are pre-assembled apart from the bulb and its elements. The bulb is prepared by hermetically sealing the fixed and movable contacts in the sidewall, and by sealing the ring 18 and flange 20 together and to the end 16 of the sidewall. In preparing the housing unit, the movable core, with the actuator rod pinned in position, is slid into the sleeve 28 and then the permanent magnet elements are mounted within the housing compartment and secured in place by the snap ring .42. Thereafter the housing, including the actuator rod 69, is inserted within the bulb with the cross pin 78 on the rod in alignment with the elongate slot 76 of the flexible element 74 so that the distal end of the rod can be inserted through the enlarged central portion of the slot. Then the housing, and thus the rod, is rotated 90 so as to engage the switching element 74 within the slots of the pin 78. Thereafter the end plate 22 is hermetically sealed to the flange 20, and the bulb evacuated and sealed through the seal-otf tubulation 90.

With reference to the FIGS. 7 and 8, a four pole, double throw relay is illustrated which is similar in many respects to therelay previously described, including the provision of a permanent magnet and similar means for actuating the flexible contacts. Specifically, the four pole relay has an evacuated envelope defined by a dielectric =bulb 100, cylindrical ring 102, annular flange 104, circular end plate 106 and tubular housing 108 of substantially the same construction and materials as the corresponding parts of the relay 10. The housing 108 includes an interior flange 110 and sleeve 112 of nonmagnetic material dividing the interior of the housing into an inner, evacuated compartment 114 and an outer compartment 116 hermetically sealed from one another by an iron or other magnetic core disc 118 at the outer end of the sleeve 112. A ring-type, axially polarized permanent magnet 120 is secured within the inner compartment 114 between an upturned edge of flange 110 and an end plate 122 held in place by snap ring 124. A movable iron core 126 is slidably mounted within the sleeve 112 and has an inner flanged end 128 normally held against the permanent magnet 120 to serve with end plate 122 as a portion of the magnetic circuit 130 of the permanent magnet.

An electromagnet is housed within the lower compart ment 116 and includes a fixed iron core 132, and an inner shell 134 of magnetic material including inner and outer end plates 136 and 138. A threaded and slotted shaft-end portion 140 of the fixed core is threaded through an internally threaded, flanged central opening 142 in the end plate 138, whereby the position of the fixed core 132 is threadedly adjusted within the outer compartment with a minimal gap 144 being provided between the disc 118 and the innermost end of the fixed core. The end plate 138 is secured in position by a snap ring 146 which fits within an annular groove in the lower interior end wall of the housing 108.

A coil 148 surrounds the fixed core and sleeve 112 within the lower compartment, and, when energized, draws the movable core 126 downwardly in the sleeve 112 away from the permanent magnet 120.

Instead of the single fixed post 72 provided in the relay embodiment of FIG. 1, four fixed tungsten posts 148, 149, 150 and 151 are hermetically sealed in the sidewall of the bulb 100 and extend radially within and without the bulb. The posts are arranged in diametrically opposed pairs, with one pair 148, 149 being aligned axially of the bulb directly above the other pair 150, 151.

Each of the movable contacts, including the rigid posts, has an associated plate-like flexible contact, or switching element 154 substantially identical in construction to the corresponding flexible element 74 of the single pole embodiment. Each of the flexible elements 154 projects between an axially spaced pair of fixed contacts 156, 158 shaped and arranged in the same relationship as described with respect to the contacts 84 and 86 of the single pole relay. Thus, in total there are four pairs of fixed contacts so as to enable the making or breaking of eight electrical circuits simultaneously upon actuation of the four flexible elements 154.

The provision of four movable contacts necessitates a modified actuator means for actuating the four switching elements 154 simultaneously. Such means includes a cylindrical actuator member, or rod, 160 fixed to the movable core 126 and extending axially inwardly of the bulb between the laterally opposed movable contacts. The rod 160 is preferably made of high-strength nonmagnetic metal such as Monel metal. The distal end of the rod 160 terminates between the upper and lower pairs of movable contacts and is threaded into a cross arm structure 162. The cross arm structure includes an outer cylindrical casing 164 and a telescopingly mounted inner member 166. The opposite outer ends 168, 16 9 of the cross arm structure engage a pair of axially extending, preferably ceramic, actuator arms 170, 171, with the ends 168, 169 being slidably received within transverse openings 172, 173 at the midportions of the arms 170, 171,

respectively.

The upright arms 170 171 each intersect an axially aligned pair of the switching elements 154 at their midportions. Each opposite end of each actuator arm 170, 171 is mounted by a molybdenum pin 174 to one of the flexible elements 154 in exactly the same manner as described with respect to the mounting of the actuator rod 69 to the flexible element 74 of the single pole of relay of FIG. 1.

Thus, it will be evident that upon energization of the coil 148 the movable core 126 will cause a simultaneous axial movement of both arms 170, 171 and, therefore, all four switching elements 154, to simultaneously open four electrical circuits between the four upper fixed contacts 156 and their associated posts 148, 149, 150 and 151, and simultaneously close four other electrical circuits between the same posts and the four lower fixed contacts 158. Subsequent de-energization of the coil will, of course, reclose the opened circuits and reopen the closed circuits.

In assembling the relay of FIG. 7, the envelope, inclu-ding the glass bulb 100, four movable contacts, ring 102 and flange 104 is prepared separately and apart from the tubular housing 108 incorporating the electromagnet assembly, permanent magnet assembly, movable core and central actuator rod. When both the envelope and the housing are prepared, the ceramic actuator arms 170, 171, with their molybdenum pins attached, are inserted through the open end of the bulb 100, and the opposite ends of each arm are slid through the elongate central apertures in the flexible elements 154 and then rotated 90 to engage both pins with their respective flexible elements. With the actuator arms in place, the cross arm assembly 162 is inserted into the bulb with the inner member 166 telescoped within the outer casing 164. When the projecting ends 168, 169 of the cross arm are aligned with the cross openings 172, 173 in the ceramic arms, the ends 168, 169 are slid into the cross openings 172, 173. The actuator rod 160, which is at this point secured to the movable core 126 and assembled in the housing 108, is then threaded into the cross arm assembly by rotating the entire housing until the proper ceramic arm and switching element positions are achieved. Finally, the end plate 106, previously attached to the housing 108, is welded at W to the annular flange 104 of the envelope to hermetically seal the interior of the envelope,

after which the envelope may be evacuated through the tubulation 180 at the closed end of the bulb 1%.

An important feature of the actuating arrangement shown in FIG. 7, in which separate spaced-apart actuating arms are provided for each one of each opposed pair of flexible contacts, as compared with certain other multiple pole relays in which the opposed flexible contacts are both actuated by a common actuating arm, is that the present arrangement minimizes any electrical stress across the actuator arms resulting from one of the opposed flexible contacts being grounded at the same time that the other such contact is not grounded. This embodiment has numerous other important advantages as recited in connection with the single pole embodiment of FIG. 1.

It will be apparent that the embodiments shown herein may be utilized with various pole arrangements and num bers of poles. For example, the embodiment of FIGS. 1 through 7 could be modified for use as a single pole relay simply by omitting one of the fixed poles, or additional switching elements could be utilize-d. The alternate embodiment described likewise could be modified.

Having illustrated and described two preferred embodiments of the invention, it should be apparent that the invention permits of modification in arrangement and detail. We claim as our invention all such modifications as come within the true spirit and scope of the appended claims.

We claim:

1. Ina vacuum relay an evacuated envelope including a tubular sidewall portion of dielectric material,

actuator means within said envelope including an actuator member extending axially within said envelope,

means at one end of said envelope for reciprocating said actuator member in a direction axially of said envelope between two axially spaced limit positions, a pair of generally diametrically opposed movable contacts, each including a rigid portion hermetically sealed to said sidewall portion of said envelope and extending outwardly and inwardly of said sidewall portion in directions generally normal to the axis of said envelope,

each said movable contact including a flexible contact portion fixed at one endto said rigid portion'within 'saidenvelope, and terminating at an opposite, free end spaced from a free end. of the flexible contact portion of the other of said movable contacts,

a pair of fixed contacts extending through and hermetically sealed in said sidewall portion at positions spaced circumferentially from one another and from the corresponding positions of both said movable contacts,

each said fixed contact, when viewed from a plane normal to the axis of said envelope, extending across the free end portion of a different one of said flexible contact portions, and being positioned for engagement with an associated said free end portion within the limits of flexibility of said flexible contact portion,

said actuator means including a pair of actuator arms olfset laterally on opposite sides of said actuator member and being connected to said member for axial reciprocation therewith,

each of said actuator arms being operatively connected to a dilferent one of said flexible contact portions at a position intermediate the fixed and free ends of said flexible portions so that axial movement of said actuator member between said limit positions causes a corresponding and simultaneous axial movement of the free ends of both said flexible portions in the same direction for alternately engaging and disengaging said fixedcontacts.

2. Avacuum relay according to claim 1 including rigid,

t5 but telescoping cross arm means operatively connecting said actuator arms to said actuator member,

said actuator arms including aperture means therein for slidably receiving projecting end portions of said telescoping cross arm means.

3. In a vacuum relay an evacuated envelope including a tubular sidewall portion of dielectric material,

actuator means within said envelope including a central actuator member extending axially within said envelope,

means at one end of said envelope for reciprocating said actuator member in a direction axially of said envelope between two axially spaced limit positions, said last mentioned means comprising annular permanent magnet means for normally maintaining said member in a first limit position and electromagnetic means operative to move said member to a second limit position, said actuator member extending through said annular permanent magnet means towards said electromagnetic means,

at least two pairs of generally diametrically opposed movable contacts, each of said pairs being aligned axially of said envelope with the other of said pairs,

each of said movable contacts including a rigid portion hermetically sealed to said sidewall portion and extending outwardly and inwardly of said sidewall portion,

each of said movable contacts also including a flexible contact portion afiixed at one end to said rigid portion and extending within said envelope in a direction generally normal to the axis of said envelope,

a pair of actuator arms laterally oitset on opposite sides of said actuator member and extending axially of said envelope,

each of said actuator arms being connected to two axially spaced ones of said flexible contact portions at positions on said flexible portions intermediate the fixed and free ends thereof,

rigid cross arm means operatively connecting said actuator arms to said actuator member so that actuation of said member causes a corresponding actuation in an axial direction of said arms and said flexible contact portions,

at least four fixed contacts hermetically sealed in said sidewall portion at positions spaced circumferentially from the corresponding positions of said movable contacts and extending within and without said envelope,

each of said fixed contacts, when viewed from a' plane normal to the axis of said envelope, extending across the free end portion of a different one of said flexible portions and being so positioned within the limits of axial movement of the associated said free end portion as to be engaged by said free end portion in one limit position of said actuating member and as to be spaced from said associated free end portion in the other limit position of said actuating member.

4. A vacuum relay according to claim 1 wherein there are two axially spaced apart fixed contacts positioned within the limits of movement of the free end of each said flexible contact portion and on opposite sides of said flexible contact portion so that actuation of said free end portion in one direction can effect a closing of one circuit and a simultaneous opening of another circuit.

5. In a vacuum relay an evacuated envelope including a tubular sidewall portion of dielectric material, actuator means within said envelope including an actuating member extending axially within said envelope, a tubular housing of nonmagnetic material extending partially within one end of said envelope coaxially withinsaid envelope,

said housing including a radially extending flange portion dividing the interior of said housing into an inner compartment in communication with the interior ofsaid envelope and an outer compartment,

a sleeve of nonmagnetic material mounted concentrically within said housing at the radially inner terminus of said flange portion,

permanent magnet means within said inner compartment,

electromagnet means within said outer compartment,

, including a fixed central core, a magnetic inner lining for said housing, and a coil surrounding said core,

a movable core of magnetic material mounted within said sleeve for axial sliding movement,

said movable core being biased inwardly of said envel- 'ope by said permanent magnet means when said coil is de-energized, and being biased outwardly of said envelope away from said permanent magnet means upon energization of said coil,

said actuator member being fixedly secured at a first end to said movable core in said inner compartment of said housing, so that energization and de-energization of said coil actuates said actuator member in a direction axially of said envelope between two axially spaced limit positions, said actuator member extending longitudinally of said envelope to a second point in said envelope out of said housing,

a movable contact including a rigid portion hermetically sealed to said sidewall portion of said envelope and extending outwardly and inwardly of said sidewall portion,

said movable contact including a flexible cont-act portion aflixed at one end to said rigid portion within said envelope,

said flexible portion being operatively connected at a position thereon intermediate its fixed end and its opposite free end to said actuator member at said second point thereon remote from said first end and within said envelope so that axial movement of said member between said limit positions causes a corresponding axial movement of the free end of said flexible contact portion in the same direction and, unless said free end is restrained, through a distance greater than the distance between said limit positions,

a fixed contact hermetically sealed in said sidewall at a position spaced circumferentially from the corresponding position of said rigid portion of said movable contact and extending within and without said envelope,

said fixed contact, when viewed from a plane normal to the axis of said envelope, extending across the free end portion of said flexible contact portion, and being so positioned within the limits of axial movement of said free end portion as to be engaged by said free end portion in one limit position of said actuating member and as to be spaced from said free end portion in the other limit position of said actuating member.

6. A vacuum relay comprising:

an evacuated envelope, including a dielectric bulb having a sidewall portion open at one end,

a fixed contact in said bulb,

a movable contact in said bulb,

an actuator member in said bulb operatively connected to said movable contact,

a tubular housing of nonmagnetic material and of lesser diameter than the open end of said bulb extending coaxially partially within said open end,

wall means of nonmagnetic material hermetically sealing a sidewall portion of said housing to said bulb,

said housing including a radially inwardly projecting flange portion dividing the interior of said housing into an inner compartment defining a portion of said evacuated envelope and an outer compartment,

a sleeve of nonmagnetic material mounted concentrically within said housing,

wall means hermetically sealing said sleeve from communication with said outer compartment so that the interior of said sleeve defines a portion of said evacuated envelope,

a movable core of magnetic material slida'bly mounted within said sleeve for limited movement axially of said envelope,

said actuator member being aflixed at an end thereof remote from said movable contact to said movable core so that axial movement of said core actuates said movable contact into and out of engagement with said fixed contact,

permanent magnet means within said inner compartment for biasing said movable core axially inwardly of said envelope, and

electromagnet means, including a fixed core, a liner for said housing and a coil surrounding said fixed core, all within said outer compartment so that upon energization of said coil said movable core is drawn away from said permanent magnet axially outwardly of said envelope.

7. A vacuum relay comprising an evacuated envelope including a dielectric bulb having a sidewall portion open at one end,

a fixed contact in said bulb,

a movable contact in said bulb,

an actuator member in said bulb operatively connected to said movable contact for moving said movable contact into and out of engagement with said fixed contact,

a tubular housing of nonmagnetic material and of lesser diameter than the open end of said bulb extending coaxially partially within said open end,

wall means of nonmagnetic material hermetically sealing a sidewall portion of said housing to said bulb,

said housing including a radially projecting flange portion dividing the interior of said housing into an inner compartment defining a portion of said evacuated envelope and an outer compartment,

a sleeve of nonmagnetic material mounted concentrically within said housing at the radially inner end of said flange portion,

at least a portion of said sleeve extending within said outer compartment,

means hermetically sealing the outer end of said sleeve compartment so that the interior of said sleeve defines a portion of said evacuated envelope,

a permanent ring magnet within said inner compartment,

electromagnet means within said outer compartment including a fixed core, an inner magnetic liner including inner and outer wall portions snugly received Within said housing, and a coil surrounding said fixed core and the portion of said sleeve extending into said outer compartment,

a movable core mounted for axial sliding movement within said sleeve,

said movable core including a radially enlarged inner end portion being in abutment with said ring magnet and defining a portion of the magnetic path of said ring magnet when said coil is de-energized,

said movable core being drawn away from said ring magnet and outwardly of said envelope, and defining a portion of the magnetic path of said electromagnet upon energization of said coil,

said actuator member being secured}? one end to said movable core at an end thereof opposite said movable contact so that upon energization and de-energization of said coil said movable contact is moved into and out of engagement with said fixed contact.

8. A vacuum relay according to claim 7 wherein said wall means hermetically sealing the outer end of said 1 1 sleeve from communication with said outer compartment is defined by an inner end portion of said fixed core projecting into said sleeve.

9. A vacuumrelay according to claim 7 wherein said wall means hermetically sealing the outer end of said sleeve from communication with said outer compartment comprises a relatively small disc of magnetic material spaced slightly from the innermost end of said fixed core.

10. A vacuum relay according to claim 7 wherein said actuator means extends through said permanent ring magnet between said mova-ble contact and said movable core.

UNITED STATES I PATENTS 2,919,323 12/1959 Drescher 200-87 3,017,447 1/1962 Heutten 335-82 X 3,154,655 10/1964 Hawkins 200-404 3,161,749 12/1964 Perry et al 200144 ROBERT K. SCHAEFER, Primary Examiner.

O K. H. CLAFFY, Examiner. 

1. IN A VACUUM RELAY AN EVACUATED ENVELOP INCLUDING A TUBULAR SIDEWALL PORTION OF DIELECTRIC MATERIAL, ACTUATOR MEANS WITHIN SAID ENVELOPE INCLUDING AN ACTUATOR MEMBER EXTENDING AXIALLY WITHIN SAID ENVELOPE, MEANS AT ONE END OF SAID ENVELOPE FOR RECIPROCATING SAID ACTUATOR MEMBER IN A DIRECTION AXIALLY OF SAID ENVELOPE BETWEEN TWO AXIALLY SPACED LIMIT POSITIONS, A PAIR OF GENERALLY DIAMETRICALLY OPPOSED MOVABLE CONTACTS, EACH INCLUDING A RIGID PORTION HERMETICALLY SEALED TO SAID SIDEWALL PORTION OF SAID ENVELOPE AND EXTENDING OUTWARDLY AND INWARDLY OF SAID SIDEWALL PORTION IN DIRECTIONS GENERALLY NORMAL TO THE AXIS OF SAID ENVELOPE, EACH SAID MOVABLE CONTACT INCLUDING A FLEXIBLE CONTACT PORTION FIXED AT ONE END TO SAID RIGID PORTION WITHIN SAID ENVELOPE, AND TERMINATING AT AN OPPOSITE, FREE END SPACED FROM A FREE END OF THE FLEXIBLE CONTACT PORTION OF THE OTHER OF SAID MOVABLE CONTACTS, A PAIR OF FIXED CONTACTS EXTENDING THROUGH AND HERMETICALLY SEALED IN SAID SIDEWALL PORTION AT POSITIONS SPACED CIRCUMFERENTIALLY FROM ONE ANOTHER AND FROM THE CORRESPONDING POSITIONS OF BOTH SAID MOVABLE CONTACTS, EACH SAID FIXED CONTACT, WHEN VIEWED FROM A PLANE NORMAL TO THE AXIS OF SAID ENVELOPE, EXTENDING ACROSS THE FREE END PORTION OF A DIFFERENT ONE OF SAID FLEXIBLE CONTACT PORTIONS, AND BEING POSITIONED FOR ENGAGEMENT WITH AN ASSOCIATED SAID FREE END PORTION WITHIN THE LIMITS OF FLEXIBILITY OF SAID FLEXIBLE CONTACT PORTION, SAID ACTUATOR MEANS INCLUDING A PAIR OF ACTUATOR ARMS OFFSET LATERALLY ON OPPOSITE SIDES OF SAID ACTUATOR MEMBER AND BEING CONNECTED TO SAID MEMBER FOR AXIAL RECIPROCATION THEREWITH, EACH OF SAID ACTUATOR AMRS BEING OPERATIVELY CONNECTED TO A DIFFERENT ONE OF SAID FLEXIBLE CONTACT PORTIONS AT A POSITION INTERMEDIATE THE FIXED AND FREE ENDS OF SAID FLEXIBLE PORTIONS SO THAT AXIAL MOVEMENT OF SAID ACTUATOR MEMBER BETWEEN SAID LIMIT POSITIONS CAUSES A CORRESPONDING AND SIMULTANEOUS AXIAL MOVEMENT OF THE FREE ENDS OF BOTH SAID FLEXIBLE PORTIONS IN THE SAME DIRECTION FOR ALTERNATELY ENGAGING AND DISENGAGING SAID FIXED CONTACTS. 